A light-emitting element (light-emitting device) is a p-n junction diode which converts electrical energy into light energy. The light-emitting element may be produced using compound semiconductors of groups III and V in the periodic table, and may implement various colors by adjusting a composition ratio of the compound semiconductors.
The light-emitting element emits energy corresponding to a band-gap energy between a conduction band and a valance band when electrons of an n-type layer and holes of a p-type layer recombine upon application of a forward voltage. This energy is usually emitted in the form of heat or light. The light-emitting element emits the energy in the form of light.
For example, a nitride semiconductor has received much attention in development fields of optical devices and high-power electronic devices due to its high thermal stability and wide band-gap energy. In particular, a blue light-emitting element, a green light-emitting element, an ultraviolet (UV) light-emitting element, and the like using the nitride semiconductor have become commercialized and are widely used.
An example of a light-emitting element according to the related art is a lateral-type light-emitting element in which an electrode layer is disposed in one direction of an epi-layer. In the lateral-type light-emitting element, an operating voltage (Vf) of the light-emitting element increases due to a narrow current flow, causing a reduction in current efficiency. Thus, there is a problem that the lateral-type light-emitting element is vulnerable to electrostatic discharge.
In order to solve such a problem, a via hole-based vertical-type light-emitting element has been developed. In the via hole-based vertical-type light-emitting element, a via hole is formed below an epi-layer and an electrode is disposed therein.
In the related art, in order to produce the via hole-based vertical-type light-emitting element, a plurality of mesa etching processes are performed for forming an n-contact, and an insulation layer is formed between the n-contact and a mesa etching hole.
According to the related art, electrons injected through a via hole cause an electron clouding phenomenon in the vicinity of the via hole, and these electrons flow through the vicinity of the via hole. Thus, light is generated in only a partial region of an active layer and luminous flux is low accordingly.